1. Field of the Invention
This invention relates to the manufacture of coldworked steel wire.
2. Description of the Prior Art
The making of steel wire is a specialized art which requires the selection of steel which, after being subjected to the strenuous forces of cold drawing through one or usually several dies to attenuate it and reduce its diameter, retains the properties essential to good wire. The wrong steel may have a work-hardening rate such that cold drawing will raise its tensile strength to the point where its loss of ductility is too great and causes wire-drawing breaks or results in surface discontinuities giving a surface of the wire not suitable for the end use, for example, plating.
Steel on the market varies widely in chemical composition and physical properties. The wire manufacturer is limited to the selection of those steels which may be coldworked to produce a good quality end product, which are not so tough in the unannealed state to produce breaks during cold working or to result in short die life and which, at the same time, can be produced economically. For this reason, low-carbon, low-silicon rim steel has generally been used where heavy reductions are required in making wire, in contrast to other available steel, for example, silicon-killed steel or boron steel, which have been thought to be tougher for wire drawing.